Fibromyalgia is a chronic pain condition that is characterized by widespread pain. Pain associated with fibromyalgia interferes with daily function, work, and social activities resulting in a decreased quality of life. In addition people with fibromyalgia have a significant amount fatigue and a fear of movement. The cause of fibromyalgia is unknown, but people with fibromyalgia show enhanced excitability of pain neurons in central nervous system and reduced pain inhibition. One of the main treatments for patients with fibromyalgia must, therefore, focus on pain relief to allow the person to function more independently both at home and at work. Transcutaneous electrical nerve stimulation (TENS) is a modality used by health professionals that delivers electrical stimulation through the skin for pain control. Basic science studies, from the PIs laboratory, show that TENS activates descending pain inhibitory pathways to inhibit excitability of pain neurons. Thus, the ideal patient population for the treatment of TENS would be one in which there is enhanced central excitability and reduced inhibition;fibromyalgia is such a condition. Although TENS is effective for several pain conditions such as osteoarthritis, chronic musculoskeletal pain, and postoperative pain [5;20;39], its effectiveness in treatment of people with fibromyalgia is virtually unknown. Furthermore, there is a general thought among clinicians that since fibromyalgia pain is widespread, TENS would be ineffective in this population. Thus, TENS may decrease pain associated with fibromyalgia by increasing central inhibition and decreasing central excitability. This decrease in pain is expected to increase function and improve quality of life. We hypothesize that application of TENS to patients with fibromyalgia will reduce resting and movement-related pain and reduce central excitability by restoring diffuse noxious inhibitory controls (DNIC), and that this decrease in pain and/or central excitability will reduce fatigue and fear of movement, thereby improving function and quality of life. We will test this hypothesis through 3 Specific Aims. Aim #1: The primary aim of the study is to test the effectiveness of the long-term use of TENS on resting and movement-related pain in people with fibromyalgia with random assignment to three treatments: no treatment control, placebo TENS and active TENS. Aim #2: A secondary aim will test if pain reduction by TENS results in a concomitant decrease in fatigue and fear of movement, and an increase in function and quality of life. Aim #3 will determine if active TENS alters pain processing in people with fibromyalgia and if improvement in clinical symptoms correlates with normalization of pain processing physiology. This innovative study will be the first to examine the effectiveness of TENS in people with fibromyalgia using multiple outcomes including pain at rest and during movement, as well as function, fatigue, and quality of life in individuals with fibromyalgia. Using multiple measures will give us a better understanding of appropriate measures for future clinical trials of non-pharmacological treatments, and for treatment of pain in people with fibromyalgia.